The overall objective of this research will be to specify behavioral and pharmacological factors that determine how drugs alter behavior. The proposed research will deal particularly with behavior controlled by scheduled presentations of aversive electric shocks or by scheduled injections of drugs. Both the maintenance and the suppression of behavior by such schedules will be investigated. Dose-effect relationships will be established by pretreatment with representative drugs. The interrelations between schedule-controlled performances and changes in heart rate and blood pressure will also be studied. Patterns of behavior have been developed and maintained in the squirrel monkey under conditions in which responses produce electric shocks. The importance of experimental history, schedule of presentation of electric shock, and schedule parameter values in engendering and maintaining this significant behavior will be studied. Several different first- and second-order schedules of electric shock presentation will be used to study the effects of drugs on this behavior. Similar schedules in which responding results in the injection of a drug or in the termination of a stimulus associated with drug injections will also be studied. These studies of patterns of behavior controlled by schedules of presentation or termination of various events will provide critical data on the role of factors such as experimental history, schedule of reinforcement, level of ongoing behavior, and type of event maintaining the behavior as determinants of the behavioral effects of drugs.